//
// RedundantExplicitNullableCreationIssue.cs
//
// Author:
//       Mike Krüger <mkrueger@xamarin.com>
//
// Copyright (c) 2013 Xamarin Inc. (http://xamarin.com)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
using System;
using System.Collections.Generic;
using ICSharpCode.NRefactory.TypeSystem;
using System.Linq;
using ICSharpCode.NRefactory.Refactoring;

namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
	[IssueDescription("Redundant explicit nullable type creation",
		Description= "Value types are implicitly convertible to nullables",
		Category = IssueCategories.RedundanciesInCode,
		Severity = Severity.Warning,
		AnalysisDisableKeyword = "RedundantExplicitNullableCreation")]
	public class RedundantExplicitNullableCreationIssue : GatherVisitorCodeIssueProvider
	{
		protected override IGatherVisitor CreateVisitor(BaseRefactoringContext context)
		{
			return new GatherVisitor(context);
		}

		class GatherVisitor : GatherVisitorBase<RedundantExplicitNullableCreationIssue>
		{
			public GatherVisitor (BaseRefactoringContext ctx) : base(ctx)
			{
			}

			public override void VisitObjectCreateExpression(ObjectCreateExpression objectCreateExpression)
			{
				base.VisitObjectCreateExpression(objectCreateExpression);

				// test for var foo = new ... 
				var parentVarDecl = objectCreateExpression.Parent.Parent as VariableDeclarationStatement;
				if (parentVarDecl != null && parentVarDecl.Type.IsVar())
					return;

				var rr = ctx.Resolve(objectCreateExpression);
				if (!NullableType.IsNullable(rr.Type))
					return;
				var arg = objectCreateExpression.Arguments.FirstOrDefault();
				if (arg == null)
					return;
				AddIssue(new CodeIssue(
					objectCreateExpression.StartLocation,
					objectCreateExpression.Type.EndLocation,
					ctx.TranslateString("Redundant explicit nullable type creation"),
					ctx.TranslateString("Remove redundant 'new'"),
					s => s.Replace(objectCreateExpression, arg.Clone())
				) { IssueMarker = IssueMarker.GrayOut });
			}
		}
	}
}

